The present invention relates to a storage system operating in communication with a host unit; and, more particularly, the invention relates to the connecting configuration of recording media having the structure of a loop connecting plural recording media.
Recently, with the increased interest in the concept of a Storage Area Network (SAN), the loop connection using an optical fiber channel is rapidly being adopted as an interface to connect a host unit with various devices. The structure of the connections between components inside a disk array unit, which does not use a bus connection, but uses a loop connection having a fiber optic channel, is becoming popular (for example, a loop connection between a controller and recording media using a fiber optic channel). For instance, Japanese patent publication No. Kokai 11-338646 discloses a disk array unit which does not use a bus, but the switching network structure for the connection between components.
The above-described patent publication is directed to the connection between the components with a single network. In a storage system connecting components with plural loops, such as this network, the following considerations will be important for mounting and setting up the recording media. 1. In case the storage system is a disk array system, the data from the host unit is distributed, generated and relocated to the data by the Redundant Array of Inexpensive (Independent) Disks (RAID) method. The data from the host unit is also recorded dispersedly into plural recording media which are set as a RAID group. Therefore, it is important to optimize the access paths and the load balancing to each recording medium. 2. There are plural loops of the recording media. Therefore, it is important to optimize the access path and the load balancing to these loops.
However, the above-described patent publication discloses nothing about the optimization of the access paths and the load balancing in connecting the recording media with multipath loops for the recording media.
As a method of load balancing optimally, it is desirable to mount the recording media at an optimum location, considering the loop for the recording medium, at the time of mounting the recording medium. In addition, at the time of forming a RAID group with the mounted recording media, it is desirable to select the recording media connected to the optimum loop for the recording media in order to build the RAID group. However, the selection of the mounting location or the selection of the recording media while taking into consideration the problem of load balancing is difficult for a person other than those who are familiar with the internal structure of the controller, such as the connecting location of the loop. Even when an operator who is in charge of the mounting and the setting executes such operation, there is a high possibility that such person will fail in distributing the recording media with a uniform load.
The object of the present invention is to provide a recording media mounting system that enables the adequate setting of access paths and load balancing without specifically considering the mounting location.
As a configuration to attain the above-described object, the storage system of the present invention consists of two or more recording media storing data received from a host unit, a controller controlling the data transfer between the recording media and the host unit, and plural loops, located between the controller and the recording media, connecting the different recording media. A recording medium is connected to an adjacent different loop than that of another recording medium, and the number of the recording media connected to each loop can be equalized by simply connecting the recording media to successive loops in turn.